Semiconductor manufacturing involves a number of automated systems used to move and transport the semiconductor (generally in the form of a wafer) at various points during the fabrication process. A number of wafers may be transported in cassettes to aid the moving of a large number of wafers at one time. During normal operation of the processing equipment, the cassettes are transported from one location to another. A device called a microscope loader moves a wafer from one location to another and then indexes to the next wafer in the cassette. A problem may occur when the arm fails to place or retrieve a wafer in a proper fashion. This may cause the arm to spill the cassette and/or break the entire contents of the cassette.
In the case of certain commercially available wafer processing machines (e.g., etchers) that include wafer transports (e.g., the wafer loader included in LAM490), wafers occasionally are not fully inserted into the receive cassettes due to cassette misplacement, faulty or misaligned belts etc. A protruding wafer may eventually catch on the edge of the plastic tunnel (e.g., in bulkhead systems). The protruding wafer may break as the cassette indexes or may tip the entire cassette, causing automatic indexing to the top and thus multiple wafer breakage. The same holds true for other commercially available wafer processing machines (e.g., the LAM Rainbows 4400, 4500, and 4600 series, etc.) which have a "pick and place" transport, which does not generally include a belt transport system. Such loaders may be more likely to pull a wafer part of the way back out of the cassette (in the event of the cassette not being properly seated) causing the wafer to catch on the plastic exit load-lock pass-through.